Previously differences in redox potential have been noted for some tumor vs. normal tissues and attempts have been made by others to use this difference in the development of new anti-tumor compounds. Certain synthetic quinones related to the natural anti-cancer agent mitomycin-C were demonstrated to have significant anti-tumor activity ascribable to the initial formation of a bis-o-quinone methide. The proposed work involves the use of bioreductive quinones as carriers of cytotoxic agents. Quinone carboxylic acids are to be combined in amide form with selected known anti-cancer agents such as N-mustard, methotrexate, etc. In the quinone form the amides are expected to show no effect on normal cells. However, upon reduction in hypoxic tumor tissue, the hydroquinone system will be generated and if the carboxamide group is suitably positioned, it will suffer neighboring-group-triggered release of the active cytotoxic species. Model studies of low molecular weight quinones of varying redox potential (0.2 - 0.5 volt) will first be carried out. Quinones substituted by alkoxy and amino groups are expected to be most appropriate in terms of expected redox potentials. Subsequently these low molecular weight models will be fixed to biodegradable polymeric carriers, e.g. poly-L-lysine in order to further enhance the selectivity toward tumor tissue. Substitution of esters or thio esters for the amide function will make possible the release of anti-tumor alcohols or thiols at the desired site.